Exercise treadmills are now widely used in gymnasiums, spas, clinics, and in private homes for aerobic exercise, physical examinations, and physical therapy. An exercise treadmill in its simplest form includes an endless belt that is moved over an underlying support bed, either by the walker's or runner's feet, or by an electric motor. The bed, in turn, is mounted on a ground-engaging support frame. If utilized, the electric motor is typically mounted on a motor pan assembly located on the frame at the front of the treadmill beneath a hood that extends upwardly a considerable elevation above the endless belt. Also located on the frame within the hood at the front of the treadmill is the drive system for drivingly interconnecting the motor with the endless belt, typically through a drive roller at the front of the endless belt. A flywheel of significant mass is typically employed as part of the drive train to help maintain a substantially uniform speed of movement of the endless belt, especially when the runner's or walker's feet land on the belt. Also located on the motor pan are controls for the motor as well as other electronic components designed to augment the operation of the motor, including large capacitors and inductors. Due to the presence of the motor, flywheel, drive train and motor controls and other components, a significant amount of area must be reserved for these components, and these components typically are installed on the motor pan section of the frame of the treadmill during assembly thereof and then must be tested.
To render the exercise treadmill more versatile, it may be positioned at various inclinations to simulate running or walking up a grade. Various mechanisms have been employed to raise and lower the front end of the exercise treadmill relative to the floor or other support surface on which the unit is positioned. For instance, in one type of exercise treadmill, the forward end of the endless belt, associated bed and belt support frame must be manually lifted and engaged or clamped to upstanding posts. It may not be possible for elderly or physically infirm persons to lift the treadmill belt, deck and frame in this manner. Examples of such exercise treadmills are disclosed in U.S. Pat. Nos. 931,394 and 2,117,957.
In another type of treadmill lift mechanism, the elevation of the forward end of the treadmill is adjusted by manually rotating threaded leg members located at the front of the treadmill frame, using a wrench or similar hand tool. This type of method is often too slow and cumbersome for most treadmill users. Moreover, typically the walker/runner must leave the endless belt to adjust the height of the threaded legs. Examples of this type of exercise treadmill lift mechanism are disclosed in U.S. Pat. Nos. 4,151,988 and 4,602,799.
In a further type of exercise treadmill, gas springs are employed to carry substantially all of the weight of the forward end of the treadmill frame to provide an essentially "zero-bias" so that the treadmill may be readily raised and lowered to a desired operating position. However, a manually operable clamping mechanism typically is employed to lock the tilting/supporting means in a desired position. Thus, to change the angle of inclination of the treadmill, the user must dismount the treadmill and move to the front to manually operate the locking device. It may not be possible for an elderly or infirm person to loosen the locking device, lift or lower the treadmill frame and then sufficiently retighten the locking device to prevent it from shifting during use of the exercise treadmill. Moreover, the gas springs must be large enough to lift not only the forward end of the treadmill frame, but also the substantial weight of the drive motor and its associated flywheel, electrical components and drive train components. Examples of the foregoing type of treadmill elevating device are disclosed by U.S. Pat. Nos. 4,591,147 (assigned to the assignee of the present application) and 4,664,371.
Another common disadvantage of known exercise treadmills, including many of those noted above, is that a substantial number of components and assembly steps are required, both during the initial preassembly of the machine at the manufacturing location, and also during the final assembly by the ultimate user of the equipment. This is not only time-consuming and expensive, but also oftentimes requires special skills and tools, which many persons do not possess.